U.S. patent number 10,541,560 [Application Number 16/266,903] was granted by the patent office on 2020-01-21 for power control method and device in wireless power transmission system.
This patent grant is currently assigned to GE HYBRID TECHNOLOGIES, LLC. The grantee listed for this patent is GE Hybrid Technologies, LLC. Invention is credited to Chun Kil Jung, Soon Sang Kwon.
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United States Patent |
10,541,560 |
Jung , et al. |
January 21, 2020 |
Power control method and device in wireless power transmission
system
Abstract
The present invention relates to a power control method and
device in a wireless power transmission system. According to the
present invention, even if a CEP packet is not transmitted from a
wireless power reception device over a certain period of time, a
wireless power transmission device may additionally determine
whether the wireless power reception device is located in a
charging area and sustainably perform charging.
Inventors: |
Jung; Chun Kil (Seoul,
KR), Kwon; Soon Sang (Siheung-si, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
GE Hybrid Technologies, LLC |
Niskayuna |
NY |
US |
|
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Assignee: |
GE HYBRID TECHNOLOGIES, LLC
(Niskayuna, NY)
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Family
ID: |
53057648 |
Appl.
No.: |
16/266,903 |
Filed: |
February 4, 2019 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20190190316 A1 |
Jun 20, 2019 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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15844624 |
Dec 18, 2017 |
10236719 |
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15036689 |
Jan 16, 2018 |
9871400 |
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PCT/KR2014/010952 |
Nov 14, 2014 |
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Foreign Application Priority Data
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Nov 15, 2013 [KR] |
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10-2013-0139258 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02J
7/00036 (20200101); H02J 50/40 (20160201); H02J
50/10 (20160201); H02J 7/0071 (20200101); H02J
7/025 (20130101); H02J 50/80 (20160201); H02J
7/00047 (20200101) |
Current International
Class: |
H02J
7/00 (20060101); H02J 50/10 (20160101); H02J
50/40 (20160101); H02J 7/04 (20060101); H02J
50/80 (20160101) |
Field of
Search: |
;320/108 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2013172499 |
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Sep 2013 |
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JP |
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201028934 |
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Jan 2018 |
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JP |
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10-2012-0132225 |
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Dec 2012 |
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KR |
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10-2013-0081812 |
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Jul 2013 |
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KR |
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2015072777 |
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May 2015 |
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WO |
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Other References
"International Search Report dated Feb. 17, 2015, issued to
International Application No. PCT/KR2014/010952", Feb. 17, 2015, 4
pages. cited by applicant .
"U.S. Appl. No. 15/844,624 Final Office Action", dated Sep. 10,
2018, 8 pages. cited by applicant .
"U.S. Appl. No. 15/844,624, Office Action", dated Jan. 30, 2018, 6
pages. cited by applicant .
"Qi System Description Wireless Power Transfer", Wireless Power
Consortium, vol. 1:Low Power, Part 1:Interface Definition, Version
1.0.1, Oct. 2010, 88 pages. cited by applicant.
|
Primary Examiner: Fantu; Yalkew
Attorney, Agent or Firm: DeLizio Law, PLLC
Parent Case Text
RELATED APPLICATIONS
This application is a Continuation of and claims the priority
benefit of U.S. application Ser. No. 15/844,624 filed Dec. 18, 2017
which is a Continuation of and claims the priority benefit of U.S.
application Ser. No. 15/036,689 filed May 13, 2016.
Claims
The invention claimed is:
1. A wireless power transmission device comprising: at least one
primary coil configured to transmit wireless power to a wireless
power reception device; a communication unit configured to receive
a control error packet (CEP) from the wireless power reception
device via the primary coil; and a control unit configured to
control a transmission of the wireless power from the primary coil
to the wireless power reception device based on the CEP.
2. The wireless power transmission device of claim 1, the control
unit configured to set an operation point for the transmission of
the wireless power based, at least in part, on a control error
value in the CEP.
3. The wireless power transmission device of claim 2, wherein the
operation point comprises at least one of an amplitude, a frequency
and a duty cycle of an alternating current (AC) voltage applied to
the primary coil.
4. The wireless power transmission device of claim 2, the control
unit configured to maintain the operation point until receiving a
subsequent CEP having a different control error value.
5. The wireless power transmission device of claim 1, wherein the
CEP is received via a signal from the wireless power reception
device, the wireless power transmission device further comprising:
the control unit configured to reset a CEP timer when the
communication unit receives the CEP and to count an interrupt
generated when decoding the signal received via the primary coil,
the control unit configured to control the transmission and stop of
the wireless power from the primary coil to the wireless power
reception device based on the CEP timer and the interrupt
count.
6. The wireless power transmission device of claim 5, wherein the
CEP timer indicates whether the CEP is received within a
predetermined period.
7. The wireless power transmission device of claim 5, wherein the
control unit stops the transmission of the wireless power when the
CEP timer is expired and the interrupt count is not greater than a
reference value, wherein the control unit continues the
transmission of the wireless power and resets the CEP timer when
the CEP timer is expired and the interrupt count is greater than
the reference value, and wherein the control unit increases a CEP
decoding failure count when the CEP timer is expired and the
interrupt count is not greater than the reference value.
8. A wireless power reception device comprising: at least one
secondary coil configured to receive wireless power from a wireless
power transmission device, the wireless power initially associated
with a first operation point of the wireless power transmission
device; and a control unit configured to transmit a control error
packet (CEP) to the wireless power transmission device via the
secondary coil, wherein the wireless power subsequently is
associated with a second operation point based on the CEP.
9. The wireless power reception device of claim 8, wherein the
control unit is further configured to: calculate a control error
value based on a difference between a desired control point and an
actual control point; and generate the control error packet (CEP)
having the control error value.
10. The wireless power reception device of claim 9, wherein the
control unit is further configured to determine the actual control
point based on the wireless power initially received from the
wireless power transmission device.
11. The wireless power reception device of claim 9, wherein the
control unit is further configured to select the desired control
point based on a characteristic of the wireless power reception
device.
12. The wireless power reception device of claim 11, wherein the
desired control point comprises at least one of a current, voltage,
or a temperature of the wireless power reception device.
13. The wireless power reception device of claim 8, wherein the
control unit is configured to periodically transmit a new CEP to
the wireless power transmission device via the secondary coil.
14. The wireless power reception device of claim 8, wherein the
control unit is configured to transmit a new CEP to the wireless
power transmission device via the secondary coil before expiration
of a CEP timer for maintaining a wireless power transfer
session.
15. A method performed by a wireless power reception device, the
method comprising: receiving wireless power from a wireless power
transmission device via at least one secondary coil of the wireless
power reception device, the wireless power initially associated
with a first operation point of the wireless power transmission
device; and transmitting a control error packet (CEP) to the
wireless power transmission device via the secondary coil, wherein
the wireless power subsequently is associated with a second
operation point based on the CEP.
16. The method of claim 15, further comprising: calculating a
control error value based on a desired control point and an actual
control point; and generating the control error packet (CEP) having
the control error value.
17. The method of claim 16, further comprising: determining the
actual control point based on the wireless power initially received
from the wireless power transmission device.
18. The method of claim 16, further comprising: determining the
desired control point based on a characteristic of the wireless
power reception device, wherein the desired control point comprises
at least one of a current, voltage, or a temperature of the
wireless power reception device.
19. The method of claim 15, further comprising: periodically
transmitting a new CEP to the wireless power transmission device
via the secondary coil.
20. The method of claim 15, further comprising: transmitting a new
CEP to the wireless power transmission device via the secondary
coil before expiration of a CEP timer for maintaining a wireless
power transfer session.
Description
TECHNICAL FIELD
The present invention relates to a wireless power transmission, and
more particularly, to a power control method and device in a
wireless power transmission system.
BACKGROUND ART
In general, in order to charge portable terminals such as a
cellular phone, a notebook, and a personal digital assistant (PDA),
the portable terminals should receive electric energy
(alternatively, power) from an external charger. The portable
terminals include a battery cell storing the supplied electric
energy and a circuit for charging and discharging (supplying the
electric energy to the portable terminals) the battery cell.
An electrical connection mode between the charger for charging the
electric energy in the battery cell and the battery cell include a
terminal supply mode that receives commercial power and converts
the received commercial power into voltage and current that
correspond to the battery cell to supply the electric energy to the
battery cell through a terminal of the corresponding battery
cell.
The terminal supply mode is accompanied by the use of a physical
cable or electric wire. Therefore, when a lot of terminal supply
mode apparatuses are handled, a lot of cables occupy a significant
work space and are difficult to arrange and external appearance is
also not good. Further, the terminal supply mode may cause an
instantaneous discharge phenomenon due to different potential
differences among terminals, occurrence of damage and fire by
foreign substances, natural discharge, deterioration of life-span
and performance of a battery pack, and the like.
Recently, in order to solve the problems, a charge system
(hereinafter, referred to as a wireless power transmission system)
and control methods using the wireless power transmission mode has
been presented. The wireless power transmission mode is also
referred to as a contactless power transmission mode or a
non-contact power transmission mode. The wireless power
transmission system includes a wireless power transmission device
that supplies the electric energy in the wireless power
transmission mode and a wireless power reception device that
receives the electric energy wirelessly supplied from the wireless
power transmitting device to charge the battery cell.
In the terminal supply mode, a power transmission is performed
through the terminal connection between a charger and a terminal,
and the power transmission is stopped when the terminal is
disconnected from the charger. On the other hand, the wireless
power transmission system requires a coupling (magnetic induction
and/or magnetic resonance) between the primary coil provided in a
charger and the secondary coil provided in a terminal for charging
owing to the non-contact charging characteristics, and the charger
always transmits power to the terminal through the magnetic
coupling. When performing a wireless power transmission by a
charger in the wireless power transmission system, the charger
should be able to stop the power transmission by detect the
terminal to be removed from a charging area. As an example, a
terminal may transmit a packet such as a control error packet
indicating that the corresponding terminal is located in a charging
area (or interface surface) to a charger, and the charger may
determine the corresponding terminal to be removed from the
charging area when the control error packet is not received for a
predetermined period (e.g., 1.8 sec). However, when a terminal
performs a battery charge through the wireless power reception, in
some cases, serious load fluctuation may occur in the terminal
(hereinafter, this is referred to a light load state), and owing to
this, a distortion may occur in the packet transmitted to a charger
from the terminal. In this case, although the terminal is located
in a charging area, a problem occurs that the charger determines
the terminal to be removed from the charging area and terminates
the power transmission.
DISCLOSURE
Technical Problem
An object of the present invention is to provide a power control
method and device in a wireless power transmission system.
Another object of the present invention is to a power control
method and device in a wireless power transmission system in which
a light duty state of a wireless power reception device is
considered.
A yet another object of the present invention is to propose an
interpretation standard for the case that a wireless power
transmission device receives a distort signal in a wireless power
transmission system.
A yet another object of the present invention is to propose a
standard for detecting whether a wireless power reception device is
removed from a charging area in a wireless power transmission
system.
Technical Solution
In an aspect, a wireless power transmission device performing a
power control is provided. The device includes at least one primary
coil configured to be coupled with at least one secondary coil
provided in a wireless power reception device located in a charging
area and configured to transmit wireless power, a communication
unit configured to receive a signal including a control error
packet (CEP) from the wireless power reception device through the
primary coil and to decode the signal, and a control unit
configured to drive a CEP timer for checking whether the CEP is
received within a predetermined period, and to count an interrupt
generated when decoding the signal received through the primary
coil, and the control unit controls transmission and stop of
wireless power to the wireless power reception device through the
primary coil based on the CEP timer and the interrupt count, and
initializes the CEP timer when the communication unit receives the
CEP.
In another aspect, a wireless power transmission method by a
wireless power transmission device performing a power control is
provided. The method includes transmitting wireless power to a
wireless power reception device located in a charging area through
at least one primary coil, receiving a signal including a control
error packet (CEP) carrying power control related information from
the wireless power reception device through the primary coil,
driving a CEP timer for checking whether the CEP is received within
a predetermined period, counting an interrupt generated when
decoding the signal received through the primary coil, and
controlling transmission and stop of wireless power to the wireless
power reception device through the primary coil based on the CEP
timer and the interrupt count, and the the CEP timer is initialized
when the CEP is received.
Technical Effects
According to the present invention, even though a CEP packet is not
transmitted for a predetermined period from a wireless power
reception device, a wireless power transmission device may
additionally determine whether the wireless power reception device
is located in a charging area and continuously perform
charging.
DESCRIPTION OF DRAWINGS
FIG. 1 is a block diagram illustrating constituting elements of a
wireless power 20 transmission system according to an embodiment of
the present invention.
FIG. 2 illustrates an example of a wireless power transmission
process.
FIG. 3 illustrates an example of a power control process performed
between a wireless power transmission device and a wireless power
reception device.
FIG. 4 is a flowchart illustrating an example of a method for
performing a power control by a wireless power transmission device
in a wireless power transmission system according to the present
invention.
FIG. 5 is a flowchart illustrating another example of a method for
performing a power control by a wireless power transmission device
in a wireless power transmission system according to the present
invention.
FIG. 6 is an example of block diagram illustrating a wireless power
transmission device and a wireless power reception device according
to the present invention.
BEST MODE FOR INVENTION
The term of "wireless power" is used to denote the energy of
arbitrary shape related to electric fields, magnetic fields, and
electromagnetic fields transmitted from a transmitter to a receiver
without employing physical electromagnetic conductors. The wireless
power may also be called a power signal and may indicate an
oscillating magnetic flux enclosed by a primary and secondary coil.
For example, this document describes power transformation of a
system intended to charge devices such as a mobile phone, cordless
phone, iPod, MP3 player, and headset wirelessly. In general, basic
principles of wireless transfer of energy rely on both of magnetic
inductive coupling and magnetic resonance coupling (namely,
resonance induction). However, various frequencies of relatively
high radiation levels, for example, below 135 kHz (LF) or above
13.56 MHz (HF) in which license-free operations are allowed may be
utilized.
FIG. 1 is a block diagram illustrating constituting elements of a
wireless power 20 transmission system according to an embodiment of
the present invention.
Referring to FIG. 1, a wireless power transmission system 100
includes a wireless power transmission device 110 and one wireless
power reception device 150-1 or n wireless power reception devices
150-1 to 150-n.
The wireless power transmission device 110 includes a primary core
block. The primary core block may include one or more primary coils
111. Although the wireless power transmission device 110 may have a
predetermined appropriate shape, one preferred shape is a flat
platform that has a power transmission surface and the respective
wireless power reception devices 150-1 to 150-n may be located on
the platform or in a charging area (e.g., a charging pad)
therearound.
The wireless reception devices 150-1 to 150-n may be separated from
the wireless power transmission device 110. When the respective
wireless power reception devices 150-1 to 150-n are positioned
around the wireless power transmission device 110, the wireless
reception devices 150-1 to 150-n include a secondary core block
coupled with the electromagnetic field generated by the first core
block. The secondary core may include a core and one or more
secondary coils 151.
The wireless power transmission device 110 transmits power to the
wireless power reception devices 150-1 to 150-n without a direct
electrical contact. In this case, it is assumed that the primary
core block and the secondary core block are magnetic induction
coupled or resonance induction coupled with each other. The primary
coil or the secondary coil may have predetermined appropriate
forms, but may be, for example, a copper wire wound around a high
permeable formation material such as ferrite or amorphous
metal.
The wireless power reception devices 150-1 to 150-n are generally
connected to an external load (not illustrated, herein, referred to
as an actual load of the wireless power reception device) to supply
power wirelessly received from the wireless power transmission
device 110 to the external load. For example, each of the wireless
power reception devices 150-1 to 150-n may consume power or carry
the consumed power to a storage object like a portable electric, an
electronic device, a rechargeable battery cell or a battery.
FIG. 2 illustrates an example of a wireless power transmission
process.
Referring to FIG. 2, a wireless power transmission device detects
that a wireless power reception device is located in a charging
area in a standby mode (step, S200). There may be various methods
for detecting the wireless power reception device by the wireless
power transmission device, and not limited to a specific method in
the present invention. As an example, the wireless power
transmission device may detect that the wireless power reception
device is located in a charging area by periodically emitting
analogue ping of a specific frequency, and based on detection
current for this, resonance shift or capacitance change. As another
example, when the wireless power transmission device periodically
transmits a detection signal and the wireless power reception
device transmits a response signal based on the detection signal,
the wireless power transmission device may detect that the wireless
power reception device is located in the charging area based on the
response signal. As yet another example, when the wireless power
transmission device periodically transmits a beacon, in response to
this, the wireless power reception device transmits a searching
signal or an advertisement to the wireless power transmission
device, and therefore, the wireless power transmission device may
detect the wireless power reception device.
As a preparation step for a wireless power transmission, the
wireless power transmission device transmits an information request
signal to the wireless power reception device (step, S210). Here,
the information request signal may be a signal for requesting an ID
and request power information of the wireless power reception
device. As an example, the information request signal may be
transmitted in a form of data packet message. As another example,
the information request signal may be transmitted in a form of
digital ping according to a predefined standard between the
wireless power transmission device and the wireless power reception
device.
In response to the information request signal, the wireless power
reception device transmits the ID and configuration information to
the wireless power transmission device (step, S220). Here, the
configuration information may include a maximum amount of power
that is provided for the wireless power reception device.
Based on the ID and configuration information, the wireless power
transmission device configures parameters for power transmission
and performs a wireless power transmission to the wireless power
reception device (step, S230). That is, the wireless power
transmission device creates a power transmission contract based on
the ID and the configuration information, and performs a wireless
power transmission to the wireless power reception device. The
process, performed by the wireless power transmission device, from
the start to the end of the wireless power transmission to the
wireless power reception device may be called a (wireless) power
transfer phase.
The wireless power reception device may provide the received
wireless power to an 10 external load such as a battery.
The wireless power transmission device monitors the parameters for
power transmission, and may abort the wireless power transmission
when any one of the parameters exceeds a stated limit.
Alternatively, the wireless power transmission process of step S230
may be expired by the request of the wireless power reception
device. For example, the wireless power reception device may
transmit a signal for requesting termination of the wireless power
transmission to the wireless power transmission device, when a
battery is fully charged.
Meanwhile, after step, S230, the wireless power reception device
continuously transmits a control error packet (CEP) periodically or
aperiodically to the wireless power transmission device (steps,
S240-1, S240-2 and S240-3). This is performed for controlling an
amount of power which is transmitted from the wireless power
transmission device to the wireless power reception device, that
is, to perform a power control. The power control processes like
steps S240-1 to S240-3 may include the power control process
according to the embodiments of FIGS. 3 to 5.
FIG. 3 illustrates an example of a power control process performed
between a wireless power transmission device and a wireless power
reception device.
Referring to FIG. 3, the wireless power reception device selects a
desired control point (step, S300). Here, the control point may
include current and/or voltage, a temperature of a part of the
wireless power reception device, and so on.
The wireless power reception device determines an actual control
point based on the wireless power received from the wireless power
transmission device (step, S310).
The wireless power reception device calculates a control error
value using the desired control point and the actual control point
(step, S320). For example, the wireless power reception device may
calculate the control error value through the (relative) difference
between a desired voltage (or current) and an actual voltage (or
current).
The wireless power reception device generates a control error
packet based on the control error value and transmits this to the
wireless power transmission device (step, S330).
The wireless power transmission device set a new operation point
based on the control error packet, if it is required (step, S340).
Here, for example, the operation point may be at least one of
amplitude, a frequency and a duty cycle of an AC voltage applied to
a primary coil.
The wireless power transmission device performs a wireless power
transmission to the wireless power reception device based on the
new operation point (step, S350). In this case, the wireless power
transmission device may maintain the operation point until a new
control error packet is received from the wireless power reception
device.
Referring to FIG. 2 again, in the case that a control error packet
is not received within a predetermined period T (e.g., 1.8 sec)
after the control error packet is received like step S240-4, the
wireless power transmission device determines that the wireless
power reception device is removed from the charging area, and stops
the wireless power transmission (step, S250). This is because it is
required to stop the wireless power transmission even in the case
that a user removes the wireless power reception device that
receives the wireless power from the charging area at any time in
addition to an excess of predetermined limit of the parameter
described above and a battery fully charged state.
However, when the wireless power reception device performs a
battery charge through the wireless power reception, in the case of
light load state in the wireless power reception device and/or the
battery, a distortion may occur in the packet transmitted to the
wireless power transmission device from the wireless power
reception device. For example, while the battery connected (or
provided) to the wireless power reception device is charging, in
some cases, owing to a fluctuation of load, the case that charge
currents are irregularly changed may happen. In this case, the
packet transmitted from the wireless power reception device may be
distorted. In such a case, although the wireless power reception
device is located in a charging area, a problem occurs that the
charger determines the terminal to be removed from the charging
area and terminates the power transmission. This may cause
unnecessary interruption of the wireless power transmission, which
becomes a problem of delaying a battery charging.
FIG. 4 is a flowchart illustrating an example of a method for
performing a power control by a wireless power transmission device
in a wireless power transmission system according to the present
invention. FIG. 4 corresponds to the process after the processes
including step S230 of FIG. 2.
Referring to FIG. 4, the wireless power transmission device drives
a control error packet (CEP) timer (step, S400). This is performed
for checking whether the wireless power transmission device
receives the CEP within a predetermined time in a power
transmission phase. The timer may be set to the predetermined
period T described in FIG. 2. In this case, the timer may be set
to, for example, 1.8 sec.
The wireless power transmission device initializes an interrupt
count (step, S405). The wireless power transmission device operates
a decoding algorithm in order to decode the message transmitted
from a wireless power reception device, and when a reception wave
form is received from the wireless power reception device, an
interrupt is generated for decoding. Particularly, when a wave form
is applied to an interrupt port of a machine control unit (MCU)
provided in the wireless power transmission device, regardless of a
normal wave form or a abnormal wave form (e.g., impulse-noise), the
interrupt is generated on a rising edge and a falling edge of the
wave form, and the interrupt count increases whenever the interrupt
is generated.
When the interrupt count is initialized, the wireless power
transmission device checks whether the interrupt is generated
(step, S410). For example, in the case that the wireless power
transmission device receives the CEP packet, about 66 counts of
interrupts may be counted per CEP packet. Since one CEP packet
includes a header, a message and a checksum field of 1 byte each,
and a start bit, a parity bit and a stop bit may be added to each
field, one CEP packet may include total 33 bits. In addition, since
the interrupt may be generated each of the rising edge and the
falling edge of the wave form, 66 counts of interrupt may be
generated for the 33 bits.
In the case that an interrupt is generated in step S410, the
wireless power transmission device increases the interrupt count
(step, S415), and checks whether the CEP timer is expired (or time
out) (step, S420). Herein, as described above, the CEP timer has a
value of T.
In the case that an interrupt is not generated in step S410, the
wireless power transmission device checks whether the CEP timer is
expired without increasing the interrupt count (step, S420).
In the case that the CEP timer is not expired in step S420, the
wireless power transmission device checks whether there exists a
message packet received from the wireless power reception device
(step, S425).
In the case that there is no message packet which is received in
step S425, the wireless power transmission device returns to step
S410.
In the case that there is a message packet received in step S425
and the packet is the control error packet (CEP) (step, S430), the
wireless power transmission device performs the power control if it
is required, and initializes the CEP timer (step, S435), and then
returns to step S405 again.
In the case that there is a message packet received in step S425
and the packet is an end power transfer packet (step, S440), the
wireless power transmission device may end the wireless power
transmission (step, 445). Herein, the end power transfer packet may
include information that indicates a reason why requesting the end
of wireless power transmission, for example, charge complete, over
temperature, over voltage or over current, and the like.
Meanwhile, in the case that the CEP timer is expired in step S420,
the wireless power transmission device checks whether the interrupt
count exceeds a reference value (step, S450). This is designed for
determining whether the wireless power reception device s removed
from the charging area based on the interrupt count value. Here,
the reference value may be set to, for example, 500. In this case,
in the case that the interrupt count value exceeds the reference
value 500, the wireless power transmission device may determine
that the wireless power reception device is still located in the
charging area, although the CEP timer is expired.
In the case that the interrupt count exceeds the reference value in
step S450, the wireless power transmission device determines that
the wireless power reception device is located in the charging
area, initializes the CEP timer (step, S455), and continues the
wireless power transmission (S460), and then returns to step
S405.
In the case that interrupt count does not exceed the reference
value in step S450, the 25 wireless power transmission device
determines that the wireless power reception device is removed from
the charging area, and stops the wireless power transmission (step,
S465).
According to the method described above, although the CEP packet is
transmitted from the wireless power reception device for a
predetermined period, the wireless power transmission device
additionally may determine whether the wireless power reception
device is located in the charging area, and perform the charging
continuously. In this case, even in the case that a distortion
occurs in the packet transmitted to the wireless power transmission
device from the wireless power reception device since a serious
load fluctuation such as a light load state of the wireless power
reception device occurs in the wireless power reception device
and/or the battery temporally, unnecessary interruption of wireless
power transmission may be prevented, and the battery may be rapidly
charged.
Meanwhile, when dividing the predetermined period T for the CEP
timer into n equal parts, the power control operation performed for
each section of n according to the present invention may be
represented as follows.
FIG. 5 is a flowchart illustrating another example of a method for
performing a power control by a wireless power transmission device
in a wireless power transmission system according to the present
invention.
Referring to FIG. 5, the wireless power transmission device drives
the CEP timer (step, S500). The timer may be set to a value of
dividing the predetermined period T shown in FIG. 2 into n equal
parts (i.e., T/n). For example, in the case that n=5 and T is 1.8
sec, 20 the CEP timer may be set to 360 ms.
The wireless power transmission device initializes an interrupt
count (step, S505).
The wireless power transmission device checks whether the interrupt
is generated (step, S510).
In the case that an interrupt is generated in step S510, the
wireless power 25 transmission device increases the interrupt count
(step, S515), and checks whether the CEP timer is expired (or time
out) (step, S520). Herein, as described above, the CEP timer has a
value of T/n.
In the case that an interrupt is not generated in step S510, the
wireless power transmission device checks whether the CEP timer is
expired without increasing the interrupt count (step, S520).
Meanwhile, in the case that the CEP timer is expired in step S520,
the wireless power transmission device checks whether the interrupt
count exceeds a reference value (step, S550). Here, the reference
value may be set to, for example, 100.
In the case that the interrupt count exceeds the reference value in
step S550, the wireless power transmission device determines that
the wireless power reception device is located in the charging
area, initializes the CEP timer (step, S555), and returns to step
S505 in the state of continuing the wireless power transmission
(S560).
In the case that the interrupt count does not exceed the reference
value in step S550, the wireless power transmission device
increases a CEP decoding failure count (step, S562). Herein, the
CEP decoding failure count represents a count of continuous
sections in which the CEP decoding is failed and the interrupt is
the reference value or lower, among the sections of n counts. That
is, in the case that it is detected that the CEP decoding is failed
and the interrupt is the reference value or lower for all sections
of n counts, it may be determined that the wireless power
transmission device fails to receive the CEP during the
predetermined period T. In this case, it may be determined that the
wireless power reception device is removed from the charging
area.
The wireless power transmission device checks whether the CEP
decoding failure count equals ton or is greater than n (step,
S563).
In the case that the CEP decoding failure count is less than n in
step S563, the wireless power transmission device initializes the
CEP timer (step, S555), and then returns to step S505.
In the case that the CEP decoding failure count equals ton or is
greater than n in step S563, the wireless power transmission device
determines that the wireless power reception device is removed from
the charging area, and stops the wireless power transmission (step,
S565).
The rest steps S525, S530, S535, S540 and S545 will be omitted
since the steps are the same as the processes of FIG. 4.
FIG. 6 is an example of block diagram illustrating a wireless power
transmission device and a wireless power reception device according
to the present invention.
Referring to FIG. 6, a wireless power transmission device 600
includes at least one primary coil 605, a power conversion unit 610
configured to apply electric driving signals to the primary coil
605 in order to generate electromagnetic field with being connected
to the primary coil 605, a communication unit 620 and a control
unit 630.
Although the wireless power transmission device 600 may have
predetermined appropriate shape, one preferred shape is a flat
platform that has a power transmission surf ace and each of the
respective wireless power reception devices 650 may be located on
the platform or in a charging area therearound.
The power conversion unit 610 may be a half-bridge inverter or a
full-bridge inverter. The power conversion unit 610 may control
frequency, duty cycle, magnitude of the electric driving signal
which is applied to the primary coil 605 by switching.
The communication unit 620 controls a communication between the
wireless power transmission device 600 and the wireless power
reception devices 650. As an example, the communication unit 620
may perform a communication with the wireless power reception
devices 650 through the primary coil 605. As another example, the
communication unit 620 may perform a communication with the
wireless power reception devices 650 through a separate radio
frequency (RF) communication means provided in each of the
communication unit 620 and the communication unit 680.
The communication unit 620 may receive an ID, configuration
information, a CEP or an end power transfer packet, etc. from the
wireless power reception devices 650.
The control unit 630 generates a control signal for power control
based on the ID, the configuration information, the CEP or the end
power transfer packet, etc., and transmits the control signal to
the power conversion unit 610.
The control unit 630 may perform control operations required to
implement the present invention described above.
The control unit 630 may initialize and drive the CEP timer.
Herein, the CEP timer may be set to the value of the reference time
T or T/n.
The control unit 630 may initialize and measure the interrupt
count, which is related to the interrupt generated when decoding a
wave form in which the communication unit 620 is received.
The control unit 630 performs the power control according to the
present invention based on the CEP timer and the interrupt
count.
As an example, when the CEP timer (e.g., T) is expired, the control
unit 630 may compare the interrupt count and the reference value on
the time when the CEP timer is expired. In the case that the
interrupt count is greater than the reference value, although the
CEP timer is expired, the control unit 630 may determine that the
wireless power reception device 650 is still located in the
charging area of the wireless power transmission device 600, and
may continue the wireless power transmission through the primary
coil 605.
As another example, in the case that the CEP timer is not greater
than the reference value, according to the termination of the CEP
timer, the control unit 630 may determine that wireless power
reception device 650 is removed from the charging area, and may
stop the wireless power transmission through the primary coil
605.
As yet another example, when the CEP timer (e.g., T) is expired,
the control unit 630 may compare the interrupt count and the
reference value on the time when the CEP timer is expired. In the
case that the interrupt count is greater than the reference value,
the control unit may increase the CEP decoding failure count. And
in case that the CEP decoding failure count is equal to or greater
than n, the control unit 630 may determine that wireless power
reception device 650 is removed from the charging area, and may
stop the wireless power transmission through the primary coil
605.
The wireless power reception device 650 may be detachable from the
wireless power transmission device 600, and may include at least
one secondary coil 655 coupled with the electromagnetic field
generated by the wireless power transmission device 600, when the
wireless power reception device 650 is located in the charging area
of the wireless power transmission device 600. In this mode, power
may be transferred to the wireless power reception device 650 from
the wireless power transmission device 600 without direct
electrical contact. The wireless power reception device 650
includes a load 670, a power pick-up unit 660 configured to collect
power with being connected to the secondary coil 655 and provide
power to the load 670, a communication unit 680 and a control unit
690.
The communication unit 680 controls a communication between the
wireless power transmission device 600 and the wireless power
reception devices 650. As an example, the communication unit 680
may perform a communication with the wireless power transmission
device 600 through the secondary coil 655. As another example, the
communication unit 620 and the communication unit 680 may be
provided with separate RF communication means, and the
communication unit 680 may also perform a communication with the
wireless power transmission device 600 through the RF communication
means.
The communication unit 680 may transmit an ID, configuration
information, a CEP or an end power transfer packet, etc. to the
wireless power transmission device 600.
The control unit 690 performs a serious of controls such that
wireless power of an appropriate level is received in the wireless
power reception devices 650.
All of the functions may be performed by a processor such as a
microprocessor according to software or program code which is coded
to perform the functions, a controller, a microcontroller, an
application specific integrated circuit (ASIC). The design,
development and implementation of the code may be apparent to a
skilled person in the art based on the description of the present
invention.
Although the present invention is described so far by reference to
the embodiments, it will be understood to those skilled in the art
that various modifications and variations can be made without
departing from the spirit or scope of the inventions. Therefore,
the present invention is not limited to the embodiments described
above, but the present invention includes all embodiments within
the range of the attached claims and the equivalence.
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